The present invention relates to lightboxes and especially to lightboxes that are adapted to be used for cropping photographic negatives. The lightbox of the present invention is especially adapted to receive a plurality of masking cards which can be fed into automatically controlled photographic printers. Such masking cards are described in the U.S. Pat. No. 4,441,807 to Bartz. They include an image bearing negative receiving aperture, a array of indicia bearing boxes at predetermined locations on the card and registration holes which are disposed at fixed positions on the card relative to the aperture.